WEEK 1

• Chemistry


  The study of the properties of and interactions between matter and energy
• Matter


  Anything that has mass and takes up space - basically, all the 'stuff' that makes up our world
• Matter is made up of atoms
• About 99 percent of your body is made up of atoms of hydrogen, carbon, nitrogen and oxygen. You also contain much smaller amounts of the other elements that are essential for life.
• Atoms


  The basic building blocks of matter
• Atom


  • Made up of smaller particles
  • Atomic nucleus is the small, dense region consisting of protons (p+) and neutrons(n°) at the center of an atom
  • Electron (e-) negatively charge particles in an atom
• Atomic number


  The number of protons in an atom
• All helium atoms have two protons, and no other elements have atoms with two protons. In the case of helium, the atomic number is 2.
• Big Bang Theory


  Postulates that 13.8 billion years ago, the universe expanded from a tiny, dense and hot mass to its present size and much cooler state
• Phases of the Big Bang

  1. Formation of subatomic particles

  2. As the universe cools, protons and neutrons can fuse to form heavier atomic nuclei

  3. Big Bang Nucleosynthesis - formation of larger matter as a result of the combination of subatomic particles to other subatomic particles. In this stage, the light elements (hydrogen, helium and trace amounts of lithium) were produced.
• Big Bang Nucleosynthesis


  Formation of light elements - Hydrogen (H), Helium (He) and small amounts of Lithium (Li) and beryllium (Be) through Nuclear Fusion
• 3 cosmic stages


  1. Big Bang Nucleosynthesis (light elements –H, He, Li were formed)

  2. Stellar formation and evolution (heavier elements- Be to Fe formed)

  3. Stellar explosion, or supernova (heavier elements than Fe were formed)
• Formation of heavy elements

  • Heavy elements were formed only billions of years after the formation of stars
  • The density inside a star is great enough to sustain fusion for extended time periods required to synthesize heavy elements
• Stellar nucleosynthesis


  The formation of heavy elements by fusion of lighter nuclei in the interior of stars
• Formation of a star

  1. A cloud of dust and gas, also known as a nebula, becomes a protostar, which goes on to become a main sequence star

  2. Gravity begins to pull the dust and gas together

  3. As the mass falls together, it gets hot. A star is formed when it is hot enough for the hydrogen nuclei to fuse together to make helium. The fusion process releases energy, which keeps the core of the star hot

  4. During this stable phase in the life of a star, the force of gravity holding the star together is balanced by higher pressure due to the high temperatures

  5. When all the hydrogen has been used up in the fusion process, larger nuclei begin to form, and the star may expand to become a red giant

  6. When all the nuclear reactions are over, a small star like the Sun may begin to contract under the pull of gravity. In this instance, the star becomes a white dwarf which fades and changes color as it cools

  7. A larger star with more mass will go on making nuclear reactions, getting hotter and expanding until it explodes as a supernova
• Supernova


  Elements heavier than iron are formed in the supernova explosions of high mass stars. When the supernova explodes, all the elements produced are thrown out into the Universe. The heavy elements found on Earth, such as gold, came from material thrown out in previous supernova explosions.
• Neutron star


  Depending on the mass at the start of its life, a supernova will leave behind either a neutron star or a black hole
• Black hole


  A place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space.
• It all starts with 1. Nebula, cloud of gas and dust particle in outer space. Due to the force of gravity, the 2. Hydrogen gas is pulled together and eventually became a protostar. Nebular fusion occurs at the center of the protostar and becomes stable. During this time, hydrogen is converted into 3. Helium forming main sequence star. The size of the star can be average or massive. A massive main sequence star that runs out of hydrogen fuel will begin to expand and cool down. This is 4. Red Super Giant, the collective term for massive stars in the universe. The red super giant continues to fuse with heavy elements and stops when 5. Iron is converted in the core of the star. At this point, red super giant will become a supernova after hundreds of years.
• Are we really made of stardust?